This invention relates to novel lymphocyte homing receptors, to methods for making these homing receptors, and to nucleic acids encoding these receptors.
Lymphocytes are mediators of normal tissue inflammation as well as pathologic tissue damage such as occurs in rheumatoid arthritis and other autoimmune diseases. In order to fully exploit the antigenic repertoire of the immune system, vertebrates have evolved a mechanism for distributing lymphocytes with diverse antigenic specificities to spatially distinct regions of the organism (Butcher, E. C., Curr. Top. Micro. Immunol. 128, 85 (1986); Gallatin, W. M., et al., Cell 44, 673 (1986); Woodruff, J. J., et al., Ann. Rev. Immunol. 5, 201 (1987); Duijvestijn, A., et al., Immunol. Today 10, 23 (1989); Yednock, T. A., et al., Adv. Immunol (44: 313-78) (1989)).
This mechanism involves the continuous recirculation of the lymphocytes between the blood and the lymphoid organs. The migration of lymphocytes between the blood, where the cells have the greatest degree of mobility, and the lymphoid organs, where the lymphocytes encounter sequestered and processed antigen, is initiated by an adhesive interaction between receptors on the surface of the lymphocytes and ligands on the endothelial cells of specialized postcapillary venules, e.g., high endothelial venules (HEV) and the HEV-like vessels induced in chronically inflamed synovium.
The lymphocyte adhesion molecules have been termed homing receptors, since they allow these cells to localize in or "home" to particular secondary lymphoid organs.
Candidates for the lymphocyte homing receptor have been identified in mouse, rat and human (Gallatin, W. M., et al., Nature 303, 30 (1983) Rasmussen, R. A., et al., J. Immunol. 135, 19 (1985); Chin, Y. H., et al., J. Immunol. 136, 2556 (1986); Jalkanen, S., et al., Eur. J. Immunol. 10, 1195 (1986)). The following literature describes work which has been done in this area through the use of a monoclonal antibody, termed Mel 14, directed against a purported murine form of a lymphocyte surface protein (Gallatin, W. M., et al., supra; Mountz, J. D., et al., J. Immunol. 140, 2943 (1988); (Lewinsohn, D. M., et al., J. Immunol. 138, 4313 (1987); Siegelman, M., et al., Science 231, 823 (1986); St. John, T., et al., Science 231, 845 (1986)).
Immunoprecipitation experiments have shown that this antibody recognizes a diffuse, .sup..about. 90,000 dalton cell surface protein on lymphocytes (Gallatin, W. M., et al., supra) and a .sup.18 100,000 dalton protein on neutrophils (Lewinsohn, D. M., et al., supra).
A partial sequence--residues--for a purported lymphocyte homing receptor identified by radioactively labeled amino acid sequencing of a Mel-14 antibody-defined glycoprotein was disclosed by Siegelman et al. (Siegelman, M., et al., Science 231, 823 (1986)).
Lectins are a carbohydrate-binding domain found in a variety of animals, including humans as well as the acorn barnacle and the flesh fly. The concept of lectins functioning in cell adhesion is exemplified by the interaction of certain viruses and bacteria with eucaryotic host cells (Paulson, J. C., The Receptors Vol. 2 P. M. Conn, Eds. (Academic Press, NY, 1985), pp. 131; Sharon, N., FEBS Lett. 217, 145 (1987)). In eucaryotic cell-cell interactions, adhesive functions have been inferred for endogenous lectins in a variety of systems (Grabel, L., et al., Cell 17, 477 (1979); Fenderson, B., et al., J. Exp. Med. 160, 1591 (1984); Kunemund, V., J. Cell Biol. 106, 213 (1988); Bischoff, R., J. Cell Biol. 102, 2273 (1986); Crocker, P. R., et al., J. Exp. Med. 164, 1862 (1986); including invertebrate (Glabe, C. G., et al., J. Cell. Biol. 94, 123 (1982); DeAngelis. P., et al., J. Biol. Chem. 262, 13946 (1987)) and vertebrate fertilization (Bleil, J. D., et al., Proc. Natl. Acad. Sci., U.S.A. 85, 6778 (1988); Lopez, L. C., et al., J. Cell Biol. 101, 1501 (1985)). The use of protein-sugar interactions as a means of achieving specific cell recognition appears to be well known.
The literature suggests that a lectin may be involved in the adhesive interaction between the lymphocytes and their ligands (Rosen. S. D., et al., Science 228, 1005 (1985); Rosen, S. D., et al., J. Immunol. (142(6):1895-1902) (1989); Stoolman, L. M., et al., J. Cell Biol 96, 722 (1983); Stoolman, L. M., et al., J. Cell Biol. 99, 1535 (1984); Yednock, T. A., et al., J. Cell Bio. 104, 725 (1987); Stoolman, L. M., et al., Blood 70, 1842 (1987); A related approach by Brandley, B. K., et al., J. Cell Biol. 105, 991 (1987); and Yednock, T. A., et al., J. Cell Biol. 104, 725 (1987)).
The character of a surface glycoprotein that may be involved in human lymphocyte homing was investigated with a series of monoclonal and polyclonal antibodies generically termed Hermes. These antibodies recognized a .sup..about. 90,000 dalton surface glycoprotein that was found on a large number of both immune and non-immune cell types and which, by antibody pre-clearing experiments, appeared to be related to the Mel 14 antigen. (Jalkanen, S., et al., A.N.N. Rev. Med., 38, 467-476 (1987); Jalkanen, S., et al., Blood, 66 (3), 577-582 (1985); Jalkanen, S., et al., J. Cell Biol., 105, 983-990 (1987); Jalkanen, S., et al., Eur. J. Immunol., 16, 1195-1202 (1986).
Epidermal growth factor-like domains have been found on a wide range of proteins, including growth factors, cell surface receptors, developmental gene products, extracellular matrix proteins, blood clotting factors, plasminogen activators, and complement (Doolittle, R. F., et al., CSH Symp. 51, 447 (1986)).
The inventors have characterized the lymphocyte cell surface glycoprotein (referred to hereafter as the "LHR") which mediates the binding of lymphocytes to the endothelium of lymphoid tissue.
Accordingly, it is an object of this invention to provide nucleic acid sequences encoding the LHR.
It is another object to provide a method for expression of the LHR in recombinant cell culture.
A further object is to enable the preparation of the LHR having variant amino acid sequences or glycosylation not otherwise found in nature, as well as other derivatives of the LHR having improved properties including enhanced specific activity and enhanced plasma half-life.